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A Lieb -ARRANGEMENT FoR THE TRANSMISSION AND REPRODUCTION oF IMAGES Filed June 2, 1959 A. LIEB Nov. 12, 1963 10 Sheets-Sheet 10 um A INVENTOR y I ATTO EY "United States Patent O Various methods have already become -known for the electrical transmission of images of iinpinging rays. In one of the oldest methods, the so-called mechanical method, the picture information is decomposed into picture points by the use of apertured disks (Nip'ikow) and at Vthe receiving end, these picture points fare reunited again by means of a mirror wheel to form the total image. This method bears the disadvantage of being very expensive,

`of providing a poor picture repro-duction, and of requiring much space for the accommodation of the apparatus.

The electrical methods `for the picture transmission generally make use of the cathode-ray tube. The pick-up is etected withV the aid of tubes which are equipped with a light-sensitive element, whereas for the reproduction of the picture there are use-d cathode-ray tubes, on the screen of which the picture to be reproduced is usually visible at a considerably reduced scale. The reproduction of the pic-ture in such arrangements is entailed by a relatively high expense. In addition thereto the surface larea of the picture to be reproduced is very limited, and the space requirement of the reproducing apparatus ris large compared with the size of the picture.

Furthermore, projection-type television receivers are known in which the picture which is produced by the cathode-ray tube, is projected with the aid of optical means onto a projection screen. The projection-types of television lreceivers bear the disadvantage tha-t the luminous density of the picture is very small, and that the space requirement as well as the technical expenditure (investment in circuit means) however, are very high.

More recently systems have been devised to reproduce television pictures with the aid of an electroluminescent screen. With conventional types of arrangements a layer of iluorescent substance consisting of an electroluminescent material is arranged within a system of crossed conductors to which, by means of a switching arrangement, signal voltages are `applied successively. However, such arrangements only enable a small number of picture points or picture elements, and the necessary switching arrangement is very expensive. A lfurther disadvantage may be seen in the high capacity between the individual conductors. Because of this there is required very expensive and highly etiicient amplifiers with a low internal resistance.

The present invention relates to yan arrangement for the transmission and for the conversion of pictures or images of an impinging radiation in which the individual picture elements act upon the electrical conductivity of radiation-sensitive elements, which, in turn, control the magnitude of an electroluminescent-exciting voltage.

According to the present invention, an electroluminesconce-exciting voltage is conducted with the aid of photoconductive elements, which are excited in accordance with the picture scanning in a timed succession to control the electrical conductivity, and by radiation-sensitive elements associated with an electroluminescent screen these last named elements corresponding to picture elements, Whereby corresponding surface areas are excited for effecting the electroluminescence.

The photoconductive elements may be constituted by a photoconducting layer which will be made conductive in lit' Eatented Nov. l2, 19d?) "ice nid

accordance with the scanning. The conductivity excitation of the photoconducting elements may also be effected by 4the radiation of an electroluminescent layer. The described arrangement bears the advantage of requiring a lowexpenditure. The individual parts or layers may be manufactured in a simple Way by a printing or spraying method. Compared Iwith the usable picture [area the space requirement of the arrangement is very low. lin addition the size of the surface area of the pic-ture to be reproduced is practically unlimited. The arrangement does not need to be manufactured or arranged in the vacuum. The possibilities of practical use of the arrangement are very versatile. By small modifications, the arrangement may be adapted to various applications of practical use.

Further features and advantages of the present invention will become more obvious from the examples of embodiments described hereinafter with reference to the accompanying drawings wherein FlG.'l is a schematic [drawing illustrating av principle upon which the invention is based,

FIG. 2 is a schematic drawing illustrating tan embodiment of the invention,

FIG. 3 shows'a modified embodiment of certain features of FIG. 2,

FIG. 4 shows a further embodiment of the invention illustrated in FIG. 2,

FIG. 5 shows a modification of the invention illustrated in FIG. 4,

FIG. 6 is a schematic diagram illustrating the pick-up portion of the invention with particular reference to scanning the picture image,

FIGS. 7 and 7A are schematic `diagrams of the pick up and reproducing portions of a modification of the invention over that illustrated in FIG. 6,

FIGS. 8-11 show in section the practical construction of the switching arrangement as shown in principle in FIG. 7,

FIGS. 9 and l0* are cross-sectional views taken on section lines CD and AB of FIG. ll,

FIG. 11 shows a cross-sectional View `taken on line EF of.u FIG. 9,

FIG. l2 is a schematic #diagram of the invention as applied to the presentation of a radar pattern,

FIGS. 13` and `14 show examples of the practical construction ofV that embodiment of the invention illustrated schematically in FIG.l l2.

The principle of the invention will be better understood trom the showing of FIG. l. On a surface of a radiationsensitive layer 1 there is deposited an electrically conductive layer 2 permitting the passage of the radiation. On

`this surface there is produced with the imaging arrangement 14, e.g. an optical lens system, the radiation image corresponding to the object to be transmitted. On the kother surface of the layer 1 there is deposited successively an electrically conductive layer 3 opaque -to the radiation, which eg. consists of carbon, a photoconductivel layer 5, as well as a further electrically conductive transparent layer 7. This arrangement represents the pick-up por-tion of the transmission arrangement.

The reproducing portion of the arrangement consists of an electroluminescent layer 4, covered on one side with an electrically conductive, optically transparent layer 9. On the other side of the electrolurninescent layer 4 there are arranged successively an electrically conductive,

opaque layer 3a, e.g. of carbon, a photoconductive layer '5a and an electrically conductive optically transparent layer 7a, The electrically conductive layers 7 and 7a are electrically'connected with eachother. To the layers Z and 9 there is applied an electrol-uminescence-exciting voltage from the source of voltage 13.

In operation a limited conductive region 8 land 8a cort meral.

responding with the desired picture resolution is produced on the photoconductive layer of the pick-up portion, and on the photoconductive layer 5a of the reproducing portion of the arrangement. These regions traverse the picture tarea in accordance with the picture scanning in any suitable manner as presently know-n in the art and are operated in synchronism. The conductivity ranges establish a conductive bridge between the layers 3 `and 7 and the layers 3a :and 7a, respectively. The resistance or the impedance of the layers 3 and 3a is substantially higher than that of the layers 1 and l4. Thus the conductive regions 8 and 8a substantially take the radiation values from the adjacent portions of the layer 1, or excite the adjoining electroluminescent portions of the layer 4, respectively, to produce the luminescence. This effect can also be achieved by making the series resistance of the layers 3 and 3a, respectively, substantially lhigher than the shunt resistance thereof. For example, the layers can be subdivided by the arrangement of :strips of insulating material, so that the layer will be subdivided into individual conductive elements. Also the mixing of electrically con-ductive portions in la size, substantially correspending to the thickness of the layer, with electrically insulating, nontransparent materials, such as with ya nontransparent lacquer, or with a lacquer not permitting the passage or" rays, may be provided.

:By means of the layers 3 and 3a, respectively, the portion of the radiation-sensitive layers 1 and the electroluminescent layer 4 in front of the conductive regions 8 or 8a respectively, are connected with the electrically conductive layer 7 and 7a, respectively. When radiation imp-linges upon this portion of the radiation-sensitive layer 1, then a conductive connection is established from the electrically conductive layer 2 to the conductivity region or area 8. The resistance iof this conductive path is `determined by the intensity of the impinging radiation. On the reproducing side the portion of the electroluminescent layer 4 in front of the conductivity range 8a is excited to produce :electroluminescence in accordance with the applied Voltage which, in turn, is dependent upon the resistance bridge of the radiation-sensitive element of the pick-up portion. In this way the radiation intensity of the radiation impinging upon the layer 1 is transferred to the reproducing portion. The conductivity regions can be produced e.g. with the aid of an optical effect of rays, or with the aid of any other electromagnetic or corpuscular radiation. The scanning over the picture area can be effected in any suitable way, e.g. by means of a rotating apertured disk, Nipkow disk, mirrored wheel or by a timed successive switching-on of sources of light or radiationpacting upon various surface areas of the photoconductive layer. The source of rays may be moved mechanically over the surface area. The radiationsensitive layer 1 can be designed to be sensitive to any kinds of rays, e.g. to electromagnetic radiation such as light, infrared, roentgen rays, ultraviolet rays, or corpuscular radiation, such as alpha or ,beta radiation. Together with the transmission there may then be carried out a conversion of the picture either into visible light or into any other desired radiation.

A further embodiment of the invention is shown schematically in FIG. 2 tof the 'accompanying drawings. Similar parts are ldesignated by the same reference nuln the pick-up portion there are arranged radiation-sensitive elemental arcas or cells 1 similarv to layer 1 of FIG. l, such as photoconductive elements arranged on the pick-up surface. These cells are connected via picture-point switching elements 12 in a limited area corresponding to region 8 indicated generally in FIG. 1, with a source of voltage 13 capable of exciting an electroluminescent material to produce luminescence, which is switched on and off at predetermined periodic time intervals. The picture-point switching elements serve to connect source 13 to the radiation-sensitive or electroluminescent elements, which together represent the picture surface, in a timed succession. rPhe other pole of the source of voltage 13 is connected via electroluminescent capacitors 4 of the reproducing portion and further picture-point switching elements 12a arranged there, to the other terminal of the elements 1. The photoconducting .resistors 15 or 15a respectively, of the picture-point switching elements 12 or .12a respectively, constitute the operating circuit thereof. The arrangement is made in such a way that the conductivity of the layers 15 or 15a respectively is affected to a great extent by the light emission of the electrolurrrinesoing capacitors 6 or 6a respectively. 1n other words, that there exists a tight optional coupling between these layers. Between the individual picture-point switching elements external electrical and optical coupling is prevented e.g. by means of electrically conductive shielding layers and/ or by llayers not permitting the passage of light rays or of rays in general. More detailed structural embodiments of the resistive and capacitive elements are presented in connection with FIGS. i841, as discussed yhereinafter in column 8.

The electroluminescent capacitors 6 or 6a respectively, are connected via further photoconducting resistors 17 or 17a respectively, with the source of voltage 18. By this connection the `layers 17 or 17a, respectively, are acted upon by the electroluminescent capacitors 6 or 6a of the preceding picture-point switching element 12 or 12a, respectively, as regards the electrical conductivity. The source of voltage 18 produces -at a predetermined time interval a voltage exciting an electroluminescence, which will `be referred to hereinafter as the voltage surge or pulse. This surge may e.g. be a momentarily applied direct-current voltage7 or any other succession of voltage variations. By the term succession of voltage variations there is to be understood eg. a succession of wave trains of an alternating-current voltage, a succession of voltage pulses, or the like. The voltage variation may also be the half-wave of 1an alternating-current voltage, or only a simple voltage pulse.

Assume an initial condition, in which the photoconducting resistor 17 of any arbitrarily chosen picture-point switching element 12 has an increased conductivity on the pick-up side, and in which the photoconducting resistor 17a belonging to the picture-point switching element 12a has a conductivity on the reproducing side which is increased with respect to that of the normal condition. Then, during the next successive excitation phase of a voltage of the source of voltage 18 electroluminescence will be produced, in both the pick-up portion and the reproducing portion in the electroluminescent capacitors 5 and 6a of the succeeding picture-point switching elements 12 and 12a. The photoconducting resistors 15 or 15a, respectively, of these switching elements are in this way rendered conductive. The electroluminescent capacitors 4 of the reproducing portion forming part of these switching elements, are excited to luminescence to a more or less strong extent by the voltagesource 13, in accordance with the radiation intensity impinging upon the radiation sensitive resistor 1. Thereby the radiation image of the corresponding extract of the picture is transmitted or transferred from the pick-up to the reproducing portion. Depending on the spectral emission properties of the electroluminescent capacitors 4 and the radiation impinging upon the layer 1, there can be carried out simultaneously a conversion of the radiation picture. With the excitation of the electroluminescent layers of the electroluminescent capacitors 6 and 6a of the individual picture-point switching elements 12 and 12a the photoconducting resistors 17 and 17a are rendered conductive. The material compositionV of these layers is so chosen that the conductivity will continue, at least during the short period of time until the next successive excitation pulse arrives. In the course of the next excitation phase of the voltage source 13 the electroluminescent capacitors 6 or respectively da of the successively following icture-pcint switching elements 12 allor/ee and 12a are now excited to luminescence, so that the same process will be repeated in the manner as described hereinbefore.

Depending on the purpose of practical application it is desirable to choose. the decay time of the photoconducting resistors 15a so that their conductivity will only have substantially died away when the new excitation of the picture-point switching element occurs. That is, Vduring next successive picture transmission cycle. In this Way the picture brightness will be increased, and that also, especially at a slow picture-transmission, there appears no flickering. However, the same may also be accomplished with a corresponding duration of afterglow of the electroluminescent layers 4. At present, however, it is still rather diiicult to prepare electrolurninescent substances to have a corresponding afterglow effect. The time duration and the time interval of the voltage surges are so adapted to the electrical and optical properties of the picture-point switching element that after two successive voltage surges the conductivity excitation of the photoconductor will have died away to such an extent that the voltage of the luminescent capacitor connected therewith has dropped below the excitation threshold value.

A somewhat modified embodiment of the picture-point switching elements is shown in FIG. 3. The same parts are again denoted by the same references as in FIG. 2.

The electroluminescent capacitors 6 are in this case connected in parallel with respective photoconducting resistor i9, which is tightly coupled optically with the electroluminescent layer. The decay time of the photoconducting layer 19 is so adjusted to the time duration of the electroluminescence voltage excitation that without the luminescence of the luminescent capacitor 6 being substantially reduced during the excitation period there will remain a sufficient excitation in the photoconducting layer 19 during the time of outage of the voltage excitation, that any possibly still existing residual excitation of the photoconductor I7, which would be likely to cause a new excitation of the electroluminescent layer 6, will be reliably excluded.

in FIG. 4 there is shown an embodiment which, on principle, corresponds to the arrangement as shown in FIG. 2. Instead of a single generator of voltage surges there are provided for the luminescence excitation of the electroluminescent capacitors 6 two such voltage sources 18 and Il alternately delivering electroluminescence-exciting voltage surges. The arrangement is that the surges coming from the individual voltage generators 18 and Il are alternately fed to the individual picture-point switching elements. rl`his arrangement has the advantage that a second excitation of the once switched picture-point switching elements, due to the residual excitation of photoconductors i7 is practically impossible. Assuming that at any respective time position in a picture-point switching element, and through the electroluminescent layer of the electroluminescent capacitor 6, the correspondingly optically coupled photoconducting layer I7 is excited, then, at this particular time position, no voltage exciting the electrolurninescence will be supplied by the corresponding voltage exciter. An excitation of the photoconducting layer and, consequently, a transfer of the switching process, is not etected until after the corresponding other voltage generator is switched on during the next successive excitation process. In this case the decay time of the pliotoconducting layer 17 is so chosen that it has died away to such an extent that the excitation of the electroluminescent capacitor connected therewith, is below the threshold value during two voltage surges.

This principle may also be applied to the reproducing side. ,Accordingly in the example of FIG. 4, either photoconducting elements 1 or electroluminescent layers lare indicated by the circles.y The terminals 22 and 23 represent the output of the pick-up portion or the input of the reproducing portion. The synchronization of the arrangement of the picture-point switching elements of both the pick-up and reproducing portion may be carried out by employing the same Voltage exciters i3 and 11 with the pick-up and reproducing portion.

In FIG. 5 there is shown an example in which the Volltage t3 exciting the luminescence of the layers d (as in FIG. 1), is derived from the voltage sounce 1S. Again the same components are designated by the same reiferences. The substantial difference of this embodiment compared with the preceding ones consists in that the voltage surges supplied by the voltage source i3 directly act upon the ylayers 1 of the pick-up portion. Both the release and the transfer of the individual picture-point switching elements is again accomplished by the photoconducting layers 17. The radiation-sensitive layers are varied in accordance with the appearing light intensity. The thus modulated succession of voltage surges is transferred to the reproducing portion. On the reproducing side there is provided a circuit arrangement 30 which is adapted to convert the voltage variations which are modulatedwith respect to their magnitude in dependency upon the light values, into voltage values of equal magnitude. The pulses of equal magnitude delivered by the switching element 3G are fed to the photoconducting layers 17a of the individual picture-point switching elements, whereas the successions :of voltage variations which are variable with respect to their magnitude, are `applied to Ithe photoconducting layers 15a of the individual picture-point switching elements. In parallel with the photoconductors l5 of the individual picture-point switching elements and the radiation-sensitive layers l on the pick-up side there is connected a resistor 2.6'. This resistor is so dimensioned that in the case `of a dark value orf the picture-point pickup elements at the switching device there will be applied a voltage level which is necessary for 'transferring the ypicture-point switching element.

v shown how the individual picture-point elements 12 or ila respectively of the pick-up and reproducing surface are arranged andelectrically connected with each other. Pthe individual picture-point switching elements are disposed in lines and are connected-through line after line. The triggering of the picture scanning is effected by an individual voltage surge or pulse produced by the genera.- tor 36. This pulse or surge is adapted to excite the electrtoilurninescent capacitor 6 of the first picture-point switching element of the iirst line. In the course of the next vo'ltage surge-as already mentioned in the description relating to FIG. Z-there is excited the next successive picture-point switching element. Upon connectingthrough the first line there is excited, via the connecting lead 25, the electroluminescing capacitor 6 of the iirst picture-point switching element l2 of the second line. In the same way there is then effected the connecting-throu gh of the further or remaining lines.

The Voltage generator I8 delivers periodically appearing voltage surges.v The source of voltage 13 supplies a voltage exciting the electroluminescence. This source is connected via the parallel photoconducting layers I5 of the individual picture-point switching elements 12 with the radiation-sensitive layers 1, the resistance of which is varied in accordance with the impinging light intensity.

In the embodiment as shown in FIG. 6 there is merely shown the pick-up portion. The reproducing portion is designed yin accordance with the arrangement as described with reference to FIGS. 2 and 5. In order to accomplish a synchronization of the picture release in the reproducing and pick-up portion, the voltage surge produced by the generator 36 is also conducted to the reproducing portion and releases there, just like in the pick-up portion, an electroiuminescent excitation orf the electroluminescent capacitor of the first picture-point switching element of the rst line.

In FIGS. 7 and 7a there is shown an embodiment in which the release for scanning the total picture as Well as also of the individual lines is eitected with the aid of synchronizing pulses. On the pick-up 4side there is arranged a voltage generator 13 supplying a periodically appearing voltage exciting the elcctroluminescence. After a period of time, at least corresponding to the period of scanning of one line, there is caused a somewhat longer-lasting voltage-'free time interval. Upon completion of the scanning or the whole picture the voltage-free time interval is expanded for a particularly long time. A switching clement i6 now also divides the voltage exciting the electroluminescence alternately into two current paths 27 and Z8. ln the course olf the current path or circuit 2S there is disposed a further switching element .33` which, upon insertion of a new succession or voltage excitations, produces an impulse in the circuit 2@ after having reached the respective end of the line. ln the same way, and by the action of the switching element 243, a non-recurrent Voltage surge will be applied to the line Sil upon insertion or start-ing of the scanning of the picture.

The structure of the individual picture-point switching elements corresponds to that as shown in FlG. 2. Oi course, instead of this construction there may also be used any of the types of the picture-point switching elements already described. For example, those according to FIG. 3. The photoconducting layers i oi the picture-point switching elements l2 are connected via the lead 27, 28, and the switch lo to the one pole to the source of voltage 13 exciting the electroluminescence. Gn the pick-up side there are arranged in this circuit the radiation-sensitive layers l, the electrical conductance of which corresponds to the intensity of the impinging radiation. The lines 21 and 3S are adapted to connect the photoconducting layers l of the pick-up portion with the reproducing portion, while the line 22 connects the electroluminescent capacitors `6 of the picture-point switching elements with the electroluminescent capacitors 37 of the line switching elements 26. On the reproducing side the corresponding lines are denoted by 2da or 22a, respectively. The capacitors 6 of the individual picture-point switching elments of one line are connected with the capacitors 37' of the so-called line switching element 26. The electroluzninescent layer of the electroluminescent capacitor 37 accordingly delivers a corresponding light pulse at every picture-point switching process of one line. rhe photoconducting resistor 39 of the line switching element 215 which is optically cou-pled in a tight manner to the electrolurninescent layer 37 is provided with such a duration of afterglow that upon appearance of a line-current pulse in the line 29 the rst picture-point switch-ing element of the successive line will be excited. in the same way also the lother lines will be connected through.

In the reproducing portion the voltage surges arriving on the line 35, and corresponding to the individual radiation intensities of the picture, are rst of all, ir" required, brought to a suicient voltage level by an amplifier A further amplifier lll which is connected in parallel therewith, and which operates within the saturation range, amplies t. e incoming pulses in such a way that always independently 'of the modulation, there ywill appear the same voltage amplitude. By the action of a switching element 16a the voltage surge-s are alternately applied at the output of the amplier 413 to the lines 43 and The switching element 4S disposed in the line Lid, applies at the beginning of the succession of surges or pulses arriving in the line 47 of one line, a non-recurrent voltage surge, whereas the switching element de which is provided in the line 47 applies, upon insertion or starting of the scanning of the picture, i.e. subsequently to the end of the long voltage-free time interval, a voltage surge or pulse to the line 48. The structure of the picture-point switching element 12a again corresponds to the arrangement according to FIG. 2. As with the pick-up portion, also in the case of the reproducing portion the electrolurninescent capacitors `6a of the picture-point lswitching elements 12a of a line are connected with each other as well as with one electrode of a luminescent capacitor 37a of a line switching element a. The photoconducting layers la are respectively connected via the electroluminescent layers fland the line 34 with the pick-up portion. The current pulse which is produced in the circuit arrangement 2d at the beginning oi a picture transmission cycle excites the luminescent capacitor o or' the first picture-point switching element of the rst upper line for effecting the light emission. On account of this the Ioptically coupled photoconducting layers l5 and i7, which are disposed in the switching element l2, become electrically conductive. The voltage supplied by the voltage generator 13a is thereby conducted to the photoconducting layer l of the first picture element of the first line. The current produced in the switching circuit is modulated in accordance lwith the intensity of the iinpinging radiation and isV conducted via the lines 3f; and 35 and the amplifier all to the reproducing portion. Gn the layer is of the first picture-point of the lirst line ci the reproducing portion there will appear an electroluminescence, the intensity of which `correspends to the radiation value received by the pick-up portion. The current pulse subsequently arriving on the line 27 of the pick-up portion is transferred via the excited phctoconductiruT layer i7 of the rst picture-point switching ele ment of the first line to the eleotnoluminescent capacitor 5 of the next successive picture-point switching element of this particular line. in this way, and in the manner as described hereinbefore, the radiation value of the pertaining element 1 is transferred to the eleotrolurninescent layer of the second picture-point switching element of the first line of the reproducing portion.

All 'of the voltage surges or pulses extending via the individual picture-point switching 4elements or the first line are also adapted to excite the electroluminescent layer of the electroluminescent capacitor 37 or 37a, respectively, `of the line switching element of the next successive line. The decay time of the excitation of the photoconducting layers 17 or 17a, Irespectively, is dimensioned in such a way that upon connecting-through of the total line there will remain a residual conductivity `of the: photoconducting layer 39. The line voltage surge or pulse appearing on the line 29 subsequently to the connecting-through of the rst line is transferred via the photoconducting laye-r 39 to Ithe electroluminescent capacitor 6 of the rst picture-point switching element ci the second line, on account of which also this entire line will be connected through. In a sirn-ilar way also the further lines will be connected through consecutively.

ln the following FIGS. S-ll Ithere is given an example relating to the practical constnuction of the picture-transmission arrangement as shown in principle in FIG. 7. FiG. 8 sho-ws -a longitudinal section of the arrangement, while FIGS. 9, l0 show cross-sectional views taken on lines CD, AB of FIG. 1l while FIG. ll shows a View tekenen line EF of FIG. 9. Same components are `again indicated by the sarne references. Along the picture surface or area there are arranged strip-like circuit elements 53 which are adapted to talee over the transfer or transmission of the lines of Ithe picture. On partial surfaces of the transparent, `electrically insulating carriers or supponts S5 and 56 which are provided vwith cut-'out portions, there are arranged electrically conductive, transparent layers 32 and 57. Therebetween is arranged an electrolfuminescent layer 5d. The `conductive layers 32 and 57 disposed between the cutouts and the electroluminesoent parts of the layer represent the electrolumine-scent capacitors 6 of the individual picture-points switching elements l?, as described in the example of FIG. 7. The cutouts of the carrier 56 are lled out with an electrically conducting, optically nontransparent material 58, eg.V carbon. In this way there is avoided a `disturbing optical coupling between the individual picture-point switching elements, and an electrical connection is established between the conducting layer 57 constituting the boundary of the one side of the electroluminescent layer of luminous material, and the photoconduct- 9 ing resistor 17 forming part of the respectively adjacent picture-point switching element.

The elements 17 are alternately connected with electrical conducting layers or lines 27 and 28, respectively (pick-up portion) or d3 and 4d (reproducing porti-on). To these conducting layers ythere is applied, as described in the example of FlG. 7, alternately an electroluminespence-exciting voltage. To the carrier 55' there is applied a photoconducting resistance layer l5. One side of this photoeon-ducting layer is connected with an electrioal conductive llayer 49' to which a voltage exciting the electroluminescence, and indicate by the reference 13 in FIG. 7, is applied. On the opposite side of the photocronducting layer l there are arranged the conducting layers 61. These conducting layers, as will be seen from the showing `of FIG. ll, extend via one edge of the switching strips Ito portions of adjacent strip surface. Each of these conducting laye-rs is assigned to one picture- -point switching element 12, and is electrically separated -eleotricaltly conductive layer 3% permitting the passage off rays, which layer 33 is "disposed on Aa carrier 62 likewise permitting the passage of. rays. The layer 38 simultaneously takes over the function of the connecting line 21 as described in the example of FIG. 7.

In the cutout portions of the carrier 55 as well as on the surface of the switching strips 53, -in order to avoid a disturbing external and mutual interaction of the picture-point switching elements, there are arranged electrically insulating, and optically nontransparen-t` llayers 63, i.e. which ldo not permit the passage `of rays. These layers 63, for example, may be electrically insulating layers of lacquer.

The first picture-point switching element of the first line, which is constituted by the capacitor 6a receives an exciting voltage surge or pulse, as already described in the example of FIG. 7, via the conducting layer 5S and the line 31 upon the respective starting of the scanning of the total picture. On account of this, and in accordance with the voltage :surges or pulses appearing in the conducting layers 32, y27 and 23 or 32, 43 and 44, respectively, successively all of the picture-pointswitching elements of the upper line will be connected through. The transparent conducting layers 32 of this switching strip are connected via the line 22 with the transparent conducting layer 38 of the electroluminescent capacitor 37. This luminescent capacitor, together with the photoconducting resistor 39, represents the line switching element as described in FIG, 7.

The photoconducting resistor 39 which is optically coupled to the luminescent capacitor, subsequently to the connecting-through of the iirst lines, conducts the line pulse only appearing in the line 29 to the iirst picture-point switching element of the second line, whereby also the switching strip of the second line is being connected through. In the sameway also the `further switching strips are successively connected through.

One practical application of the invention `for the representation and transmission of a radar pattern will now be 4described with reference to FIGS. 12, 13 `and 14. In FIG. l2 the principle is shown in a schematic representation. The voltage pulse which is periodically produced by the pulse generator 65 is fed via the modulator 66 to the transmitter 67. The high-frequency pulse which is thus released by the transmitter is fed in the conventional manner via the transceiver switch 68 to the antenna 69. The received high-frequency is led via the mixer stage 7 0 and the XIF-amplifier 7 i to the detector 72. The rectiiied high frequency, if necessary, is reamplied in a picture amplifier 72?` and is then fed to a switching ele- #will become conductive.

ment 74, which depending on the picture amplitude 73,

.modulates a voltage which excites an electroluminescent subs-tance or material to produce the luminescence.

The switching element 74 may be eg. an electron t-ube with a control characteristic, to the control grid of which there .is applied an alternating-current voltage as well as also the picture signal. In the anode circuit of the tube, depending on the amplitude of the picture signal, there is produced a lower or higher alternating-current voltage exciting the electroluminescence.

The voltage las produced by the switching element 7d is fed to the imaging device 77, consisting of the photoconductor 75 and of the luminescent capacitor '76. Both the photoconductor 75 and lthe luminescent capacitor 76 are electrically coupled to each other and, e.g. designed as two surfaces touching each other, ile. are in contact with one another, or as two surf-aces which are connected with each other :electrically by means of intermediate layers, the size of said surfaces corresponding to the size of the picture area. Immediately in front of the photoconductor '75 of the imaging arrangement 77 there is rotating a switching strip 53 containing picture-point switching elements 12a which are arranged along a straight line. The time of rotation of the switching strip corresponds to that of the antenna. The synchronous rotation of the antenna and of the switching strip is accomplished, for example, by two synchronous motors '79 and 80. The voltage generator 8l applies to the lines 51 and 52 alternately voltage pulses exciting the electroluminescence. The timed succession of these surges or pulses determines the connecting-through velocity oi the picture-point switching elements of the switching strip. The pulse generator 65 is connected with the switching arrangement 78. This arrangement, when triggered by a pulse, delivers a voltage surge exciting the luminescence capacitor 6a of the first picture-point switching element 12a of the switching strip lfor producing the.V electroluminescence. In this way the optically coupled photoconductor la of this picture-point switching element On account of this, and during the next voltage surge appearing in the line 52 the luminescent capacitor `da of the next picture-point switching element will be excited .to produce the electroluminescence, and the optically coupled photoconductor of this particular element will be rendered conductive. The further processes are repeated one after the other with respect to `the individual picture-point switching elements. The elements are connected through successively.

Between the luminescent capacitors 6a of the individu-al picture-point switching elements and the photoconducting surface '75 there exists a tight optical coupling. Every light pulse of the luminescent capacitors produces on the surface 75 a corresponding conductivity area. In view or" the rotating motion of the switching strip, of the straight-lined arrangement of the individual picture-point switching elements and of the connecting-through which is effected successively with respect to time, the conductivity area or range extends along radii which, inaccordance with 'the antenna, pas-s through the entire face plate area (picture surface).

The passage velocity along the radii is determined by the succession of surges and is adapted to the telemet-ric scale of the object to be imaged. On the electroluminescent picture surface the objects are imaged in accordance with the high frequency impinging upon or received by lthe antenna and reflected by the object, in a manner correctly observing both the distance and the angle.

In FIGS. 13 and 14 there is :shown in a longitudinal and cross-.sectional View embodiment of the construction of the imaging arrangement 77, and of the switching strip 53. The imaging arrangement consists of the optical transparent base 62 on which successively there are arranged the transparent, electrically conducting layer 9, the electrolumi-nescent layer 4, the electrically conductive, but optically nontransparent layer 19,' the photolil conductive layer as well as the electrically conductive, optically transparent layer 7. The base or carrier 62 may consist eg. oi glass or mica, the layer l@ may consist of carbon, andthe electrically conductive, optically transparent layer 9 may consist of tin oxide, which may be obtained by the reaction of tin chloride or tin tetrachloride with the heated glass or mica base. To the layers 9 and 7 there is applied the voltage which is produced by the circuit arrangement '74, modulated in accordance -with the picture information and adapted to excite the electroluminescence.

The embodiment of the switching strip, on principle, corresponds to the switching strip described in the ernbodiment of FIGS. 8 and 1l, and assigned to the individual line elements. The same components are denoted by the same references. Onto the partial surfaces of the base plates or supports 55 and -55 which are provided with cut-out portions, there are deposited the electrically conductive, transparent layers 32 and 57. riherebetween is arranged the electroluminescent layer 54. The conducting .layers as well as the electroluniinescent layers arranged between the cut-out portions of the bases 55 and S6 represent the luminescent capacitors 5 (corresponding to the description of FlG. 12), of the individual picture-point switching elements.

The cut-out portions of the bases Sti, `for preventing optical coupling between the individual luminescent capacitors `6` and for establishing an electrical connection between the conducting layers 57 belonging to the individual luminescent capacitors, and the photoconducting resistance layer 17 belonging to the respectively adjacent picture-point switching element, are iilled out with an electrically conductive, but optically nontransparent material 58. The photoconductive layers 17 are also alternately connected with the conductive layers i3 and 44. These lines are alternately supplied by the voltage 4generator 31 with voltage pulses or surges exciting the electrolurninescence. The voltage pulse as produced by the circuit arrangement 78 upon release of a transmitting pulse, and adapted to excite the electroluminescence, is applied to the conductive layer 57a of the rst picture-point switching element. Into the cutouts or cut-out portions of the base 55 as well as onto the surface of the switching strip, in order to avoid a disturbing external or mutual interaction of the picture-point switching elements, there are deposited electrically insulating la ers 63 which are yopaque to the passage of any radiation, such as a dark layer of lacquer. The distance between the switching strip and the imaging arrangement is chosen to be as small as poss-ible. Via the axis S2 the switching strip is connected with the rotation device Sil, eg. with a motor running synchronously with the rotation of the antennas. ln FIGS. 13 and :14 the lead-in conductor of the voltage to the rotating switching strips is not shown. This `feed-in may be eiiected exg. with the aid of slip rings.

it is to be understood that the invention -is in no way restricted to these given examples of embodiment.

What is claimed is:

1. An electrical switching arrangement 'for scanning in a predetermined successive sequence a plurality of picture areas of an image translation surface comprising: `a plurality of cellular switching elements arranged in a repetitive coordinate array on said surface, each of .toffee said switching elements being adapted to provide a source of voltage to a corresponding adjacent elemental picture area of said surface; each of said switching elements comprising an electrolurninescent capacitor formed of two conductive transparent electrode layers transverse to said surface and having lluminescent material therebetween; a iirst kand a second photoconducting resistor layer, one positioned on each side of said capacitor, said rst resistor being optically coupled thereto and said second resistor being electrically coupled the-reto and optically shielded therefronna source of periodic voltage variations for exciting luminescence in said capacitor; a iirst `circuit means connecting sa-id source to said iirst resistor layer, said first resistor being coupled in a iirst series circuit to said surface at said corresponding elemental picture area; a second circuit means connecting said source, said second resistor and said electrolurninescent capacitor of an adjacent switching element in a second series circuit; means for optically shielding said adjacent switching elements; the periodicity of said voltage variations being substantially equal to the decay period of said photoconducting resistors.

2. An electrical switching arrangement according to claim 1 wherein that portion `of said second series circuit between said second resistor and said electroluminescent capacitor is a non-transparent conducting connection layer incorporating as `a part thereof said optical shielding means.

3. An electrical switching arrangement according to claim l wherein the ele-mental picture areas of said surface comprise a layer of photoconductive material.

4. An electrical switching arrangement according to claim 1 wherein the elemental picture areas `of said surface comprise a layer of luminescent material.

5. A'tlrst electrical switching arrangement according to claim l, wherein said elemental picture areas .tof said surface comprise a layer of photoconduotive material, and includ-ing a second switching arrangement, also according to claim l, wherein the elemental picture areas comprise a layer of luminescent material and 'further including a third circuit means for operationally connecting together said rst circuit means of said first switching arrangement Vand said -first circuit means tof said second switching arrangement; and switching means operationally connected to said third circuit means for alternately switching said periodic voltage variations between the second photoconducting resistors of said adjacent switching elements of both said first and second switching arrangements.

6. The device of claim 1 including a second switching .arrangement -for reproducing said picture areas, wherein the :elemental picture `areas comprise a layer of luminescent material and switching means to provide said source of voltage from said switching elements adjacent said picture area to said luminescent layer.

References Cited in the tile of this patent UNITED STATES PATENTS 2,732,469 Palmer lan. 24, 1956 2,739,l93 Anderson Apr. 16, 1957 2,858,363 Kazan Oct. 28, 1958 2,944,155 Mayer July 5, 1960 2,947,912 Hoiman Aug. 2, 1960 

1. AN ELECTRICAL SWITCHING ARRANGEMENT FOR SCANNING IN A PREDETERMINED SUCCESSIVE SEQUENCE A PLURALITY OF PICTURE AREAS OF AN IMAGE TRANSLATION SURFACE COMPRISING: A PLURALITY OF CELLULAR SWITCHING ELEMENTS ARRANGED IN A REPETITIVE COORDINATE ARRAY ON SAID SURFACE, EACH OF SAID SWITCHING ELEMENTS BEING ADAPTED TO PROVIDE A SOURCE OF VOLTAGE TO A CORRESPONDING ADJACENT ELEMENTAL PICTURE AREA OF SAID SURFACE; EACH OF SAID SWITCHING ELEMENTS COMPRISING AN ELECTROLUMINESCENT CAPACITOR FORMED OF TWO CONDUCTIVE TRANSPARENT ELECTRODE LAYERS TRANSVERSE TO SAID SURFACE AND HAVING LUMINESCENT MATERIAL THEREBETWEEN; A FIRST AND A SECOND PHOTOCONDUCTING RESISTOR LAYER, ONE POSITIONED ON EACH SIDE OF SAID CAPACITOR, SAID FIRST RESISTOR BEING OPTICALLY COUPLED THERETO AND SAID SECOND RESISTOR BEING ELECTRICALLY COUPLED THERETO AND OPTICALLY SHIELDED THEREFROM; A SOURCE OF PERIODIC VOLTAGE VARIATIONS FOR EXCITING LUMINESCENCE IN SAID CAPACITOR; A FIRST CIRCUIT MEANS CONNECTING SAID SOURCE TO SAID FIRST RESISTOR LAYER, SAID FIRST RESISTOR BEING COUPLED IN A FIRST SERIES CIRCUIT TO SAID SURFACE AT SAID CORRESPONDING ELEMENTAL PICTURE AREA; A SECOND CIRCUIT MEANS CONNECTING SAID SOURCE, SAID SECOND RESISTOR AND SAID ELECTROLUMINESCENT CAPACITOR OF AN ADJACENT SWITCHING ELEMENT IN A SECOND SERIES CIRCUIT; MEANS FOR OPTICALLY SHIELDING SAID ADJACENT SWITCHING ELEMENTS; THE PERIODICITY OF SAID VOLTAGE VARIATIONS BEING SUBSTANTIALLY EQUAL TO THE DECAY PERIOD OF SAID PHOTOCONDUCTING RESISTORS. 